1. Field
The present disclosure relates to peripheral nerve interface system and method for prosthetic hand control, which may measure, analyze and control efferent motor nerve signals and afferent sensory nerve signals by regenerating a peripheral nerve and control an artificial prosthetic hand by means of the measurement, analysis and control of the signals.
2. Description of the Related Art
If a nerve is damaged, for example if a nerve is cut, stimuli generated in or out of a living body are not normally transferred, and so a seriously bad influence is exerted to an organism. The cutting may occur due to diseases such as arteriosclerosis, diabetes and Buerger disease, injuries caused by car accidents or industrial accidents, infections, tumors, congenital deformities or the like. The number of disabled persons suffering from congenital or acquired deformities is increasing every year, and the rehabilitation and return to the normal social life for disabled persons suffering from cutting become a great issue.
Most of disabled persons suffering from cutting rehabilitate by wearing a prosthetic hand, a prosthetic leg or an assist device and training. If such rehabilitating tools are used, a user may not easily feel a touching sense or conduct a complicated work such as writing. In addition, if a patient suffers from serious cutting, wearing and controlling such an assist device is substantially impossible.
Existing artificial prosthetic hand or prosthetic foot determines the intent of a behavior by means of body power or surface electromyogram but is disregarded by patients due to low recognition rate and malfunctions. In order to solve such problems, a technique for moving artificial prosthetic hand and foot according to the intention of a user is demanded. In other words, as one of methods using nerves remaining in a cut portion, a nerve control technique and a nerve feedback technique where a sensor is attached to artificial prosthetic hand and foot to feed sense information to the nerves are demanded.
In relation to existing nerve signal detection and stimulation, techniques such as a depth type, a planar type, a sieve type and a cuff type are being studied, but these techniques have limits as follows.
The planar type (which is also called Microelectrode Array (MEA)) is directed to measuring a nerve signal by means of nerve cell cultivation. However, since the planar type is generally utilized for studying a method for analyzing signals of a nerve system or a method for inputting information to a nerve system, it is not suitable to apply the planar type to a technique of connecting a nerve system and an artificial device.
The depth type represents a method of directly inserting an electrode into a nerve tissue and using the electrode. The electrode collects electric signals from surrounding nerves. However, an insertion-type electrode may cause necrosis or accumulations of surrounding cells due to a long time use, which may prevent active signals of nerves from being stably measured. In other words, due to the feature of nerves which are composed of several bundle-type efferent axons, there is a limit in distinguishing signals accurately.
The sieve type disclosed in U.S. Pat. No. 6,908,470 is called a nerve-regenerating electrode. The sieve type uses regenerating ability of nerves, where a sieve-shaped electrode is placed between cut nerves so that the efferent axons of the nerve cells are regenerated while passing between the sieve-shaped electrodes. By doing so, a nerve signal may be measured. However, the sieve electrode may be used only when being located between cut nerves, namely only when nerves are alive at both terminals, and so its application scope is limited.
The cuff type is directed to measuring a nerve signal by surrounding nerves directly. Since the cuff type measures a nerve signal from an outside of nerves surrounded by an insulator, it is difficult to measure an accurate signal and separate afferent and efferent signals.
Therefore, the existing methods described above have limits in detecting nerve signals of cut peripheral nerves composed of bundle-type efferent axons and freely controlling a prosthetic hand through stimulation.